Genetic load and junk.

Mung, to petrushka, elsewhere:

Everyone does not understand “genetic load” and those that do claim to understand are probably wrong. Why don’t you start an OP on genetic load and the genetic load argument? That would be interesting. Betting you won’t.

This is such an OP. I believe the genetic load argument*** was initially proposed by Susumu Ohno in 1972, whose paper also introduced the then-scare-quoted term “junk”. It’s brief, accessible, and worth a read for anyone who wishes to offer an opinion/understand (not necessarily in that order).

The short version: sequence-related function must be subject to deleterious mutations. Long genomes (such as those of most eukaryotes) contain too many bases for the entire genome to be considered functional in that way, given known mutation rates. The bulk of such genomes must either have functions that are not related to sequence, or no function at all.

Interestingly, the paper is hosted on the site of an anti-junk-er, Andras Pellionisz, a self-promoting double-PhD’d … er … maverick. Also of interest is that, contrary to some ID narratives, the idea was initially resisted by ‘Darwinists’, if that term is understood not as people who simply accept evolution, but as people who place most emphasis on Natural Selection. Perfectionism is not the sole preserve of Creationists.

More recent work has characterised the nonfunctional fraction, and this lends considerable empirical support to Ohno’s contentions.

[eta: link to comment]
***[eta: in relation to genome size, not the first time anyone, ever, discussed genetic load!]

209 thoughts on “Genetic load and junk.

  1. Frankie: LoL! Only if you assume it was unguided evolution that did it. Too bad it happens all of the time*

    * other experiments with E coli have also produced the ability to utilize citrate in an aerobic environment

    Aerobic citrate transport (lets just abbreviate it ACT) is not the only thing to evolve in this experiment. Why focus on that one result? Yes, it has evolved in other experiments (for example in that creationist experiment where they deliberately requested and used one of the clones from Lenski’s Cit+ lineage that already had most of the potentiating mutations accumulated, talk about stacking the deck), and yes even in the wild.

    But that still doesn’t mean it happens all the time. Because it doesn’t. They have 12 independent lineages of E coli in the experiment, and they’re all radically different. Only one of those lineages have evolved ACT in those 65.000 generations so far (and it probably began with only one bacteria at some point in that lineage).

    meaning most likely it was due to a built-in response

    No, it’s not a “built-in response”. If it was a built-in response, one wonders why it took on the order of thirty-thousand generations to activate?

    Of course, since we know how it evolved (ACT), we also know that you are simply advancing a counter-factual assertion.

    But let’s see if it makes sen.
    Mutations had to happen for ACT to evolve (one of them a gene-duplication of the citrate transporter). The particular combination of mutations that give rise to the ability only happened in one of those 12 lineages, despite them all starting from the same ancestral colony (meaning they started out being clones, genetically identical), and despite the fact that the growth conditions are identical. Yet all 12 lineages are now very different from each other and only one has evolved ACT.

    There’s nothing about any of these facts that imply a “built-in-response”. A built-in response would respond the same way, for the same organism, in the same environment, at about the same time every time. That’s how a “built-in response” would behave.

    Really, you’d expect a “built-in response” to operate a bit faster than managing to activate only once in about thirty quadrillion individuals, 30.000 generations down the line. That’s one amazingly shitty “built-in response”. It has an activation success rate of about 0,000000000000000000000003%. If your designer is “guiding” this response, he’s the most incompetent one I’ve ever heard of.

    Simply put, the “built-in response” rationalization fails at all conceivable levels.

  2. Has anyone on this thread actually shown that Moran’s numbers are wrong?

    Just thought I would ask every hundred posts or so.

    It was my original question, although the discussion of the meaning of load is interesting.

  3. OMagain: Frankie: However given a Common Design there is a pattern we would expect.

    And what is that pattern?

    Frankie: “exactly what we see!!!111!!” Take THAT EVILUTIONISTS!!!!111!!!


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